Method For Slide Embedding
EMS Catalog #70170
An Improved Procedure for Embedding Frozen Sections Directly on Glass Slides for subsequent Ultrastructural Examination. P. McMillan (1), and L. Cosio (2). (1) Pathology Det., Rhode Island Hospital, Providence, RI; (2) Electron Microscopy Sciences Corp., Hatfield, PA.
It is generally accepted that frozen sections provide the best preservation of biological reactivity when histochemical analyses of whole tissue are performed. Although a variety of techniques have been developed for the embedding of tissues intended for ultra-scructural examination, each is associated with its own peculiar problems and/or disadvantages (for example, see A through C below).
- Cut sections are stained and embedded in a plastic Petri dish, aluminum weighing dish, or other suitable container. Disadvantages - Sections tend to become curved, or folded or rolled up during the staining and embedding procedures. The subsequent selection, cutting out, and mounting of suitable areas is often very difficult. (1)
- Frozen sections are stained and dehydrated in place on a gelatin coated glass slide. The final embedding step involves inverting a resin-filled gelatin capsule or "beem" capsule over the section and then carefully placing the slide in an oven for polymerization. (2) Disadvantages - Sections must be small (usually 6mm or less), and the inverted capsules frequently leak causing an unsatisfactory embedding.
- Frozen sections are stained and dehydrated in place (as in procedure B) on glass slide. In the final step the top surface of the slide (with sections) is completely covered with embedding resin. The slide is then placed in a level oven for polymerization. (3) Disadvantages - A relatively viscous embedding resin (Epon 812) or equivalent) must be used and the shelves of the oven must be perfectly flat to prevent the embedding resin from running off the slide.
We have developed a new embedding mold which has three wells that are tailored to fit standard 1' x 3' slides. In addition, the wells are 0.013" deep (twice as thick as a standard slide) so that an aliquot of low viscosity embedding resin can be layered over the top surface of the slide and securely held in place until polymerization is complete. Subsequently, the layer of embedding resin (with the enclosed sections) can be removed by placing the slide on a hot plate (90°C), inserting a single edge razor blade between the glass and the resin, and prying upward. Please see the samples of our embedding mold and embedded slides that accompany this exhibit.
(1) Ferayorni LS et al., In Isolation, Characterization, and Use of Hepatocytes, R A Harris and N W Cornell ed., p 271-276, Elsevier Science, 1983.
(2) Isobe Y et al., Acta Histochem Cytochem 10: 161-171, 1977.
(3) McMillan et al., Lab Invest 50: 408-420, 1984.